1. Technical Field
This invention relates in general to telecommunications and, more particularly, to burst-switched optical networks.
2. Description of the Related Art
Data traffic over networks, particularly the Internet, has increased dramatically recently, and will continue as the user increase and new services requiring more bandwidth are introduced. The increase in Internet traffic requires a network with high capacity routers capable of routing data packets of variable length. One option is the use of optical networks.
The emergence of dense-wavelength division multiplexing (DWDM) technology has improved the bandwidth problem by increasing the capacity of an optical fiber. However, the increased capacity creates a serious mismatch with current electronic switching technologies that are capable of switching data rates up to a few gigabits per second, as opposed to the multiple terabit per second capability of DWDM. While emerging ATM switches and IP routers can be used to switch data using the individual channels within a fiber, typically at 2.4 gigabits per second or ten gigabits per second, this approach implies that tens or hundreds of switch interfaces must be used to terminate a single DWDM fiber with a large number of channels. This could lead to a significant loss of statistical multiplexing efficiency when the parallel channels are used simply as a collection of independent links, rather than as a shared resource.
Different approaches advocating the use of optical technology in place of electronics in switching systems have been proposed; however, the limitations of optical component technology has largely limited optical switching to facility management/control applications. One approach, called optical burst-switched networking, attempts to make the best use of optical and electronic switching technologies. The electronics provides dynamic control of system resources by assigning individual user data bursts to channels of a DWDM fiber, while optical technology is used to switch the user data channels entirely in the optical domain.
Previous optical burst-switched networks designed to directly handle end-to-end user data channels have been disappointing and have shown the limitations of current optical components. Optical burst-switched networks are extremely time-constrained; in a limited time, both the data burst (DB) and the associated control information (the burst header packet or “BHP”) must be scheduled for transmission on an outgoing optical link with available room. Scheduling of the BHPs has been found to be extremely challenging.
Therefore, a need has arisen for a method and apparatus for efficiently scheduling burst header packets in a burst-switched network.